In the welding together of plate-like members in the fabrication of storage tanks, hulls, ship walls, and the like, it is common to weld an upstanding first plate along the bottom edge thereof to a frame member, following which a second upstanding plate is positioned on the frame member adjacent the first plate and welded to the frame along the bottom edge and to the first plate along their confronting vertical edges. The lower course of the structure being fabricated is completed by welding successive plates onto the frame member and to the previously welded plates. If the object being fabricated has more than one course of plates, the plates of the second course are welded along their bottom edges to the top edges of the plates of the first course and the confronting vertical edges of the plates of the second course are welded to one another.
In the welding of successive plates to one another it is necessary to locate and maintain the plates in such relative positions as to provide a proper weld. This requires that the confronting vertical edges of two plates be in coplanar relation and spaced apart the proper distance. This usually necessitates the use of clamping devices. In addition, it is quite common for temporary lugs, bars, and straps to be welded to one or both plates prior to the welding of the latter together for the purpose of maintaining them in the desired relative positions. The use of such temporary devices is objectionable for a number of reasons, not the least of which is the time required to apply and subsequently remove them. In addition, the welding of the temporary devices to the plates sometimes adversely affects the temper of such plates or causes them to warp.
Devices of the kind heretofore proposed for use in the welding of plates to one another have been confined, so far as is known, to devices which are capable of positioning two plates of the same course, but are not capable of being used to position and support plates of two adjacent vertical courses.
Apparatus constructed in accordance with the invention overcomes the disadvantages of heretofore known apparatus intended for similar purposes.